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Compressing Gaussian Splats | PlayCanvas Weblog

Compressing Gaussian Splats | PlayCanvas Weblog

2023-12-06 06:18:48


3D Gaussian Splatting is a brand new technique for digitizing and rendering actual world objects. With gaussian splatting, you possibly can digitize a scene from a number of pictures utilizing companies like Luma Labs or Polycam. These companies take the set of pictures and generate a 3d Gaussian Splat scene in PLY format.

For instance, it is a Gaussian Splat scene rendered in PlayCanvas.

What’s a Splat?

Gaussian Splat Scenes will not be made up of polygons and textures. As a substitute, they’re made up of many (as much as tens of millions) of particular person, unconnected blobs known as splats. A splat is only a particle in area with measurement, orientation, coloration and opacity.

Beneath you possibly can see a single brown splat chosen. The splat bounding field exhibits its orientation and measurement:

Splat Example

The gaussian a part of the title comes from the form of splat itself: the splat opacity has a gaussian falloff from its heart to its edge.

Engine Help

The PlayCanvas staff has been including assist to the engine for loading and rendering Gaussian Splat PLY recordsdata:

Engine Example

Because the ensuing recordsdata are sometimes messy and require cleansing, we launched SuperSplat, a device for cleansing and processing gaussian splat PLY recordsdata:

SuperSplat Example

PLY Format

Nevertheless, the default gaussian splat PLY format as exported by coaching instruments is giant.

It’s because the uncompressed format shops a considerable amount of knowledge per splat:

Title Information Format Bytes
Place 3 x float 12
Orientation 4 x float 16
Scale 3 x float 12
Spherical harmonics / coloration 48 x float 192
Whole   232

For instance, the unique guitar.ply scene file takes 132.8 MB (32 MB excluding spherical harmonic knowledge).

Compressed PLY Format

So we launched a compressed PLY format to be used in runtime functions. The compressed PLY file format ignores the unused spherical harmonic knowledge and shops the remainder of the weather in quantized integers.

The format could be summarized as follows:

  • Cut up the scene into chunks of 256 splats
  • For every chunk, retailer the min and max (x, y, z) for place and scale in floating level
  • For every splat within the chunk, retailer a normalized and quantized worth for place and scale (relative to chunk extents) and orientation and coloration

This knowledge structure leads to the next knowledge per chunk:

Title Information Format Bytes
Place certain 6 x float 24
Scale certain 6 x float 24
Whole   48

And the next knowledge per splat:

Title Information Format Bytes
Place uint32 (11, 10, 11) 4
Orientation uint32 (2, 10, 10, 10) 4
Scale uint32 (11, 10, 11) 4
Colour uint32 (8, 8, 8, 8) 4
Whole   16

Consequently, the compressed model of guitar.ply takes solely 8.7 MB.

See Also

Do It Your self

The simplest method to generate a compressed PLY file your self is utilizing the SuperSplat tool. Load the PLY file into SuperSplat and export it once more utilizing the ‘Compressed Ply File’ possibility:

SuperSplat Export

In case you are within the file format specifics, see this code which demonstrates decompress the file knowledge.

See this editor project for an instance of loading and rendering a compressed gaussian splat PLY file. Or you possibly can run it here.

Abstract and Future

We’ve got launched a brand new compressed PLY format for gaussian splatting which is roughly 4x smaller than uncompressed knowledge and can be utilized in realtime functions.

In future we hope to:

  • retailer splats hierarchically for optimized rendering and culling
  • implement realtime splat LOD
  • check skinning and animation of gaussian splats
  • additional compress gaussian splat knowledge
  • optimize WebGPU rendering


The compressed format is essentially primarily based on the high quality work of Aras Pranckevičius and his blog posts.

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